Design and implementation of a passive neutron counter to continously monitor holdup in glove boxes

LaFleur, A. M.*; Nakamura, Hironobu ; Menlove, H.*; Marlow, J.*; Swinhoe, M. T.*; Mukai, Yasunobu ; Kurita, Tsutomu 

To improve the safeguards and nuclear material accountancy of holdup measurements, a continuous neutron monitor (CNM) that continuously monitors the singles rate from holdup in gloveboxes was design and implemented at PCDF. The holdup currently in the gloveboxes at PCDF is from LWR recycle plutonium. In the near future, different Pu isotopic compositions from Fugen spent fuel will be transferred to PCDF. The different Pu isotopics of MOX-B fuel will result in much higher neutron emission rates compared to that from LWR spent fuel. Thus, the CNM is needed to establish baseline measurements of the existing holdup as a function of time prior to the introduction of the plutonium into the process equipment. It is considered that these baseline measurements can then be compared to post-process measurements to holdup after introduction of MOX-B fuel to determine the relative increase in holdup in the gloveboxes, and will help to avoid anticipated problems concerning safeguards or nuclear material accountancy.